8 



PROCEEDINGS OF THE NATIONAL MUSEUM 



in male of previous species. Labrum, mandible, paragnath, first max- 

 illa, and second maxilla like those of the female. Maxilliped resembling 

 that in P. protothacae, but claw 150/x along axis, and sclerotization of 

 innermost seta on the second segment slightly different (fig. 41). 



Postoral area as in female. 



Legs 1-4 segmented and armed as in female. Last segment of endo- 

 pod of leg 1 (fig. 42) with terminal spinules slightly coarser than in 

 female. 



Leg 5 (fig. 43) with the free segment 32ju x 14/x, without ornamenta- 

 tion, terminal seta 55 n, and subterminal spine 10m, slender and seti- 

 form, without lamellae. 



Leg 6 as in P. protothacae, the two setae 31^ and 44 n in length. 



Spermatophore not seen. 



Color in life in reflected light opaque white, eye pale red. 



Etymology. — The specific name mesodesmatis is formed from the 

 generic name of the host. 



Comparison with related species. — P. mesodesmatis is very close 

 to P. protothacae, but differs from it in several features. In P. mesodes- 

 matis the prosome of the female is swollen, the ratio of length to 

 width of the caudal ramus is 3.4:1 (instead of 4:1 as in P. protothacae), 

 the first antennae are distinctly shorter, and certain other parts are 

 relatively smaller as shown below. 



Comparison of certain features of Paranthessius protothacae and 

 P. mesodesmatis is as follows : 



